Reversible feed mechanism for machine-guns



Aug. 8, 1933.

F. K. HOWARD REVERSIBLE FEED MECHANISM FOR MACHINE GUNS Filed Jan. 20, 1933 Inventur Farr-est K.H|:|ward Attorney Patented Aug. 8, .1933

REVERSIBLE FEED MECHANISM FOR 1 MACHINE-GUNS 1 f Forrest K. flowardpEast Falls, Church, Va.

' Application January 20,1933. Serial No. 652,645

8 Claims. (Cl. 89-33) (Granted under the act of March 8, 1883, as

amended April 30, 1928; 370 0. 757) The invention described herein may be'manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to a reversible feed mechanism for machine guns and is an improvement on the mechanism shown in U. S. Patent No. 1,803,351 of May 5, 1931.

In the patent, a breech bolt is provided with two intersecting cam paths interrupted at the point of intersection to receive a switch block which is adjustable to selectively complete either one of the cam grooves depending on theoperation of a right or left handed cartridge feeding mechanism. Inthe construction shown in the patent the breech bolt has been weakened in the vicinity of the pivot of the switch block with the result that the bolt soon cracks.

The purpose of thepresent invention is to provide an arrangement whereby the switch block may be mounted without unduly weakening the breech bolt and whereby the block may be firmly supported against rotation. a

To these and other ends, the invention consists in the construction, arrangement and combination of elements described hereinafter and pointed out inthe claims forming a part of this specification. r

A practical embodiment of the invention is illustrated in the accompanying drawing,

wherein: g 7

Figs. 1 and 2 are plan views of a breech bolt showing the two positions of adjustment of the switch block.

. Figs. 3 and 4 are detail views in plan and elevation of the switch block.

Fig. 5 is a view partly in side-elevation an partly in section showing the relation of the bolt to the cartridge feeding mechanism.

Figs. 6 and 7 are plan views showing the positions of adjustment jof a modified switch block.

Referring to Figs} 1 to 5 by character of reference there is shown a portion of a machine gunincluding a casing 5 having a transverse feedway 6 in which a reversibly mounted slide 7 is reciprocated by means of a lever 8. The lever 8 is pivoted in the casing through the pin 9 and has a stud 10 riding in a cam path in the upper face of a breech bolt 11 that is movable axially of the 5 1 advance a cartridge belt from right to left and the other being employed when the belt is to be the recess.

engages a stem 21 on the switch block. The locking pin constitutes the pivot of the extractor lever 22 which is provided in the conventional rmecham'sm of the Browning gun for withdrawing tioned to enter the barrel.

advanced from left'to right. The two cam paths are formed by grooves 12 and 13 interrupted at their point of intersection by a recess 14 in which is placed a switch block 15'having a single groove 16. The switch block is adjustable to selectively complete either one of the grooves 12 and 13 and likewise to block off the groove not completed. In order not to weaken the breech block and also in order to provide extended lateral support tothe switch block, the recess 14 is defined by .parallel side walls 17 and 18 extending longitudinally of the bolt and each positioned an appreciable distance from the side of the breech bolt. The end walls 19-19 of the recess are preferably formed on a curve drawn from the center of the 7 intersection of the cam paths.

The switch block 15 is symmetrical about a longitudinal axis and is substantially of diamond shape having opposite parallel faces aa, and b-- b with rounded ends c--c. The groove 16 is formed on the long axis and extends between the rounded ends c-c. When the switch block is placed in the' recess 14 it is held against rotation by virtue of the engagement of its sides a or b with the parallel side walls 1'7 and 18 of The switch block is additionally held against rotation and also against withdrawal from the recess by means of a locking pin 20 which is insertable transversely in the bolt and a cartridge from the belt and lowering it across the front face of the bolt so that it may be posi- The stem 21 is provided with two sets of opposite notches d-d and ee, one of which will be presented to the locking pin in the four positions of adjustment of the switch block. These four positions of adjustment are obtained by moving the switch block through an angle less than 45 to selectively complete the cam paths or by moving it through an angle of over 180 to produce the same result.

As 1 clearly shown in Fig. 1 the inner side of the extractor lever 22 is in prolongation of the side wall 17 of the recess and is utilized to provide lateral support in one of the positions of adjustment.

A small spring 23 carried by the stem of the switch block and acting on the floor of the recess 14: tends to raise the block and facilitate its removal when the locking pin is withdrawn.

In the modification shown in Figs. 6 and 7 no the lateral support for the left side of the switch block 24 is providedin one instance by means of alug 25 fitting into a recess 26 in the block, and in the other instance the right side of the block is laterally supported throughout its length by the right wall '27 of the recess.

I 01mm; I

1. In a machine gun, a breech bolt having two intersecting cam paths interrupted at the inter-:.

section by a recess having parallel side walls, a

symmetrical switch block receivable in the recess,

said block being substantially diamond-shaped with a cam path formed on the long axis of the diamond, the opposite sides of the block engaging the opposite sides of the recess when the block is in position of adjustment with its cam path completing either one of the inter ing the opposite sides of therecess when the block is in position of adjustment with its cam path'completing either one of the interrupted cam paths, and means for engaging the block in any position of its adjustment to hold it against rotational displacement. V

' 3. In a'machine gun, a breech bolt having two intersecting cam paths interrupted at the inter} section by a recess having parallel side walls, a symmetrical switch block receivable in the recess. said block being substantially diamond-shaped with a cam path formed on the long axis of the diamond, the opposite sides of the block engaging the opposite sides of the recess when the block is in position of adjustment with its cam path completing either one of 'the interrupted cam paths.

4. In a machine gun, a breech bolt having two intersecting cam paths'interrupted at the intersection by a recess having parallel side walls, .an extractor lever mounted in the bolt and having its inner side in prolongation of one of the side walls of the recess, a switch block having a cam path receivable in the recess, said block having four oppositely parallel sides, a pair of sides being in engagement with the walls of the recess and the extractor when the block is in any position of adjustment with its cam path completing either one of the interrupted cam paths.

5. In a machine gun, a breech bolt having two intersecting cam paths interrupted at the intersection by a recess having parallel side walls, a switch block having a cam path receivable in the recess, said block having four oppositely parallel sides, a pair of sides being in engagement with the wallsoff the recess when the block is in any position of adjustment with its cam path completing either one of the interrupted cam paths.

6. In a machine gun, a breech bolt having two intersecting cam paths interrupted at the intersection by .a recess having one side Wall extending longitudinally of the bolt, a switch block receivable in the recess, said block being substantially diamond-shaped with a cam path formed on thelong axis oithe diamond, one side of the block engagingthe side wall of the recess when the block is in any position of adjustmentwith its cam path completing either one of the interrupted cam paths, and means for additionally engaging the block in any position of its adjustment to hold it against rotational displacement. In a machine gun, a breech bolt havingtwo intersecting cam paths interrupted at the intersection'by a recess having one side wall extending longitudinally of the bolt, a switch block receivable in the recess, said block having a cam path, one side of the blockengaging the side wall of the recess when the block is in any position of ad.- justrnent with its cam path completing either one of the interrupted cam paths, and means for additionally engaging the block in any position of its adjustment to hold it against rotational displacement. p I

8.. In a machine. gun, a breech bolt having two intersecting cam paths interrupted at the intersection .by a recess having cne side wall extending longitudinally of the bolt, a switch block receivable in the recess and having a cam path for selectively completing either one of the interrupted paths, said block adjustable to selectively complete the interrupted cam paths by a movem nt through less than 45 or more than 180, and the block engaging the side wail of the recess inany position .of adjustment.

"FORREST K. HOWARD. 

